1. Field of the Invention
The present invention relates to a method of transmitting a broadcast message, and more particularly, to a method of transmitting a broadcast message in a mobile wireless communication system.
2. Discussion of the Related Art
A broadcast message uses a data burst message to transmit data to all or specific groups of mobile stations. At the same time, the mobile stations are in a specified mode when receiving the broadcast message.
If the broadcast message is transmitted via a Forward Common Control Channel (F-CCCH) and a Secondary Broadcast Control Channel (S-BCCH), control information of the broadcast message to be transmitted is sent via the F-CCCH. For example, the control information includes information related to whether the broadcast message has been transmitted, and Enhanced Broadcast Page information which indicates the location of the broadcast message transmitted on the S-BCCH.
According to the conventional method, the aforementioned broadcast message is transmitted via the S-BCCH. More specifically, the broadcast message is not transmitted via a Primary Broadcast Control Channel (P-BCCH), which is used to transmit an overhead message only, nor via the F-CCCH. However, the Enhanced Broadcast Page information can be transmitted using a Multi-slot Enhanced Broadcast Paging scheme or a Periodic Enhanced Broadcast Paging scheme.
FIG. 1 is an example showing the Multi-Slot Enhanced Broadcast Paging scheme. In detail, the Multi-Slot Enhanced Broadcast Paging scheme is a scheme which transmits the Enhanced Broadcast Page information during F-CCCH slots so that all the mobile stations can receive the broadcast signal. Here, all the mobile stations are in the slotted mode to receive the broadcast signal. As illustrated in FIG. 1, if a Maximum Paging Cycle period of the F-CCCH is 16 slots, the Enhanced Broadcast Page information can be continuously transmitted in the 16 slots. Furthermore, the Enhanced Broadcast Page information can be received by all the mobile stations receiving different slots on the F-CCCH.
FIG. 2 is an example illustrating a Periodic Enhanced Broadcast Paging scheme where a BCAST_INDEX is 1. In FIG. 2, information on whether the Periodic Enhanced Broadcast Paging scheme is being used can be determined by the BCAST_INDEX of a Multi-Carrier Radio Resource (MC-RR) Parameters Message. For example, the value of the BCAST_INDEX represented by ‘000’ indicates that the Periodic Enhanced Broadcast Paging scheme is not used. On the other hand, if the value of the BCAST_INDEX is not ‘000,’ then the Periodic Enhanced Broadcast Paging scheme having (B+7) broadcast paging cycle period is being used. Here, the value of ‘B’ can be determined according to Equation 1.B=21+i×16 1≦i≦7   Equation 1
In Equation 1, i represents a value of the BCAST_INDEX transmitted via the MC-RR parameters message.
In FIG. 2, the value of the BCAST_INDEX is ‘1’ and when applied to Equation 1, the value of B is 64 and the broadcast paging cycle is 71. The Enhanced Broadcast Page information is transmitted via a first F-CCCH slot of the broadcast paging cycle, and the Enhanced Broadcast Page information includes BCCH_INDEX and TIME_OFFSET. Consequently, transmission locations of the S-BCCH and the broadcast message can be identified by the Enhanced Broadcast Page information.
A plurality of BCCH is classified into Broadcast Control Channel Number (BCN). In detail, the BCN value of the P-BCCH is 1, and the BCN value of the S-BCCH can be any number between 2˜8. The broadcast message is transmitted via the S-BCCH after 40×(1+TIME_OFFSET)ms with respect to the transmission point of the Enhanced Broadcast Page information. Here, the BCN value of the S-BCCH is BCCH_INDEX+1.
As described above, in order to transmit a broadcast message, Enhanced Broadcast Page information, which provides information on whether the broadcast message is to be transmitted and the transmission location of the broadcast message, has to be first transmitted via the F-CCCH. Thereafter, the actual broadcast message is transmitted via the S-BCCH. However, the problem with this transmission scheme is that the actual broadcast message cannot be transmitted via the F-CCCH.